The present invention relates to a screen and an image display apparatus, and specifically, to a screen technology suitable for an image display apparatus for displaying an image by transmitting light according to an image signal.
For a so-called rear projector that displays an image by transmitting light according to an image signal, a transmissive screen that transmits light is used. The rear projector has been made thinner by adopting a configuration that light according to an image signal is entered from a diagonal direction relative to the screen. In the case where the light is entered from the diagonal direction relative to the screen, it is necessary for the screen to have a configuration that the diagonally entered light is angle-converted into a direction toward an observer. Further, it is considered that the larger the incident angle of light entering the screen, the easier total reflection of the light occurs at the boundary of the screen. When the light is taken into the projector due to total reflection on the screen, it becomes difficult to display bright images. Furthermore, when the light is taken into the projector, sometimes ghost images are produced due to multipath reflection of stray lights. Accordingly, in order to obtain bright high-quality images, the screen must have a configuration that the diagonally entered light is efficiently advanced toward the observer. A screen technology for efficiently advancing the diagonally entered light has been proposed in JP-A-2003-149744, for example.
A Fresnel lens enters light from a slope at the lower side as a side where a light valve is provided as seen from a screen, and totally reflects the incident light on a slope at the upper side. However, in the technology proposed in JP-A-2003-149744, brightness variations are greatly produced in the light exiting from the Fresnel lens. Accordingly, there is a problem that it is difficult to eliminate the brightness variations of light from the screen even when the light is uniformized by providing a diffusion layer or the like at the light exiting side of the Fresnel lens. An advantage of some aspects of the invention is to provide a screen by which incident light can be efficiently advanced in a predetermined light exiting direction and brightness variations can be reduced, and an image display apparatus.